Derivatives of isocyanuric acid and processes for preparing the same

ABSTRACT

WHEREIN R1 IS HYDROGEN OR LOWER ORGANIC RADICAL, R3 AND R4 ARE HYDROGEN, METAL, AMMONIA OR ORGANIC RADICALS. THE COMPOUNDS ARE USEFUL AS WATER TREATING AGENTS.   AZINE-2,4,6-TRIONE   1-(N(-CH(-R1)-P(=O)(-OR3)-OR4)2-CH2-CH2-)-HEXAHYDRO-S-TRI   DERIVATIVES OF ISOCYANURIC ACID OF THE GENERAL FORMULA

United States Patent 3,838,124 DERIVATIVES OF ISOCYANURIC ACID AND PROCESSES FOR PREPARING THE SAME Edwin A. Matzner, St. Louis, and Robert S. Mitchell, Webster Groves, Mo., assignors to Monsanto Company, St. Louis, M0.

N0 Drawing. Continuation-impart of abandoned application Ser. No. 105,707, Jan. 11, 1971. This application Mar. 20, 1973, Ser. No. 343,076

Int. Cl. C07d 55/38 US. Cl. 260248 NS 10 Claims ABSTRACT OF THE DISCLOSURE Derivatives of isocyanuric acid of the general formula wherein R is hydrogen or lower organic radical, R and R are hydrogen, metal, ammonia or organic radicals. The compounds are useful as water treating agents.

The present invention is a continuation-in-part of application Ser. No. 105,707 filed Jan. 11, 1971, now abandoned.

The present invention relates to a new class of isocyanuric acid derivatives and processes for preparing such compounds. More particularly, the present invention has as its primary object providing phosphorus-containing isocyanuric acid derivatives and processes for preparing the same.

According to the present invention, there is provided a new and useful class of isocyanuric acid derivatives corresponding to the following formula:

wherein R is hydrogen, phenyl, substituted phenyl or C alkyl and R and R, can be the same or different and are selected from the group consisting of hydrogen, metal ions, ammonium ions, alkyl ammonium ions, alkyl, alkenyl, aryl and alkaryl radicals.

The aforementioned metal ions may be monovalent or polyvalent and include without limitation alkali metals such as sodium, lithium and potassium; alkaline earth metal such as calcium and magnesium; aluminum; zinc; cadmium; manganese; nickel; cobalt; cerium; lead; tin; iron; chromium; and mercury. Where the metal ions are monovalent each R and R may individually be such metal ion. Where the metal ions are divalent each divalent metal ion will replace a pair of R radicals which may be R R R R or R +R, and may be from the same or ditferent isocyanuric acid derivative molecules. Likewise a trivalent metal ion such as chromium will replace three R radicals in a similar manner.

Useful alkyl ammonium ions are those derived from amines having molecular weights below about 300. Particularly preferred are alkyl amines, alkylene amines and alkanol amines containing from 2 to about 10 carbon atoms and not more than two amine groups, including for example ethyl amine, diethyl amine, triethyl amine,

3,838,124 Patented Sept. 24, 1974 propyl amine, propylene diamine, hexyl amine, 2-ethyl hexyl amine, N-butylethanol amine and triethanol amine.

Useful alkyl and alkenyl radicals are those containing from 1 to about 18 carbon atoms and include both aliphatic and alicyclic radicals. Preferred aliphatic radicals are those containing from 1 to about 8 carbon atoms while preferred alicyclic radicals are those having a total of from about 4 to 10 atoms up to 2 of which may be nitrogen, sulfur, oxygen or phosphorus with the remainder being carbon.

Useful aryl and alkaryl radicals are those containing up to about 40 carbon atoms and include phenyl, naphthyl, anthryl and phenanthryl, and hydroxy, halogen or amino substituted derivatives thereof. Preferred alkyl aryl radicals are those wherein the alkyl has from 1 to about 6 carbon atoms.

It is to be understood that all of the compounds falling within the above Formula I and as heretofore defined are generically described herein as isocyanuric acid derivatives. In other words, then, the acids, salts and esters and physical and chemical mixtures thereof are all generically described herein as isocyanuric acid derivatives.

In general, the isocyanuric acid derivatives are prepared by reacting together (a) a phosphorus-containing material which is orthophosphorous acid, a combination of PO1 and H 0, or a dialkyl phosphite ester,

(b) an aldehyde, preferably formaldehyde,

(c) 2-aminoethyl isocyanuric acid, i.e.

The Z-arninoethyl isocyanuric acid is prepared by the reaction of cyanuric acid with ethylene imine according to the procedure of N. Milstein, Journal of Chemical Engineering Data, Volume 13, -No. 2, page 275, April 1968.

Aldehydes that can be used in the processes of this invention to prepare the isocyanuric acid derivatives include those of the formula:

(II) (II) R -cH wherein R is hydrogen, phenyl, substituted phenyl, or C alkyl. Substituted phenyls include chlorophenyl, nitrophenyl, and C alkylphenyl. Examples of aldehydes useful in the practice of the present invention include formaldehyde and paraformaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, tolualdehyde, chlorobenzaldehyde, and nitrobenzaldehyde. In conjunc tion with the use of these aldehydes, it is to be understood that they can be used per se or mixed with alcohol and/ or water in order to facilitate easier handling of the reaction mass, temperature control and the prevention of foaming. For example, if formaldehyde is selected, Formalin, which is a trademark for a 27% (United States) or 40% (British) formaldehyde solution, can be used. Generally, these are aqueous solutions containing from about 0% to about 40% methanol.

The preferred phosphors containing compound is orthophosphorous acid which is commercially available. It is to be understood, however, that while H PO is generally preferred the individual ingredients PCl and H 0 which react to make orthophosphorous acid can be used separately in the manufacturing process.

When it is desired to prepare the ester form of the compounds falling within Formula I above the corresponding dialkyl phosphite ester (RO) PHO wherein R is an alkyl group containing 1 to about 20 and preferably from 1 to about 8 carbon atoms is used in place of the orthophosphorous acid as the phosphorus containing specie. For ease of description, however, the remainder of the specification will generally refer to orthophosphorous acid as the phosphorus containing reactant.

The orthophosphorous acid can be utilized in the process of the present invention either as the acid per se or in the form of one of its salts such as its monoor diammonium salts or its monoor dialkaline metal salts. Such orthophosphorous acid salts will generally be utilized in combination with an amount of a supplementary acid sufiicient to maintain the pH of the reaction mixture below about 4 and to convert the orthophosphorous acid salt into the more reactive acid form. The supplementary acid may be any strong acid as for example hydrochloric, sulfuric, hydrobromic, phosphoric, or sulfonic acid.

The actual preparation of the isocyanuric acid derivatives of the instant invention may be by any of several conventional routes which are taught in the literature. Where the aldehyde reactant is formaldehyde or paraformaldehyde the preferred route is the Mannich-type reaction described in the J. Org. Chem. 31, 1603-1607 (1966), in an article by Moedritzer and Irani. According to this method, stoichiometric amounts of the amine and phosphorous acid and a catalytic amount of hydrochloric acid are heated to reflux temperaure and 100% excess of aqueous formaldehyde or paraformaldehyde solution is added dropwise over a period of one to two hours. After refluxing for an additional period of one to two hours the resulting aminomethyl phosphonic acid is isolated by standard procedures.

In the reaction of 2-aminoethyl isocyanuric acid, phosphorous acid and formaldehyde, it is preferred that the reaction temperature be above about 85 C. and most preferably at reflux temperature. It is also preferred that hydrochloric acid be employed as a source of chloride ion and to maintain the reaction pH below about 4 and preferably below about 2. The low pH is most favorable to the desired reaction and the chloride ion serves to inhibit the oxidation of phosphorous acid to phosphoric acid. Other strong acids can, of course be used to control pH- and the chloride ion may be introduced in other forms such as, for example, NaCl, KCl or other inorganic salts.

The reaction process is carried out with conventional readily available chemical processing equipment. For example, a conventional heated glass lined reaction vessel equipped with an agitator and a reflux condenser is quite adequate to carry out this reaction.

Specific examples of the Mannich-type reaction utilizing formaldehyde as a reactant and phosphorous acid or diethyl phosphite as the phosphorus containing reactant are illustrated in the examples included herein.

Where the aldehyde reactant is an aliphatic or aromatic aldehyde other than formaldehyde as defined in Formula II above, then the isocyanurate derivatives are preferably prepared by a process comprising the following steps:

R-CHO PCls OlJJH-POC]:

ClCH-POCI; +1310 C1 GHPO(OH)1 The above described process is known in the art and is effective to produce the isocyanuric acid derivatives of the present invention although product yields are normally low, often within the range of 5 to 40 percent.

The reaction of an aliphatic or aromatic aldehyde with PCl and the subsequent hydrolysis of the reaction product to the acid is described in Doklady Akad. Nauk SSSR, 75, 219-22 (1950) in an article by Kabachnik and Shepeleva. A typical reaction between an aldehyde and PCI;, according to Step (1) above is described as follows:

A mixture of one mole of an aldehyde and 1-1.5 moles of phosphorus trichloride are heated in a sealed tube at a temperaure of from about to 250 C. for three to six hours. Required temperatures depend upon the specific aldehyde being used and temperatures of from to 200 C. are often adequate. After the reaction period, the reaction product is cooled and vacuum distilled to remove hydrogen chloride and unreacted phosphorus trichloride. The reaction product which is the dichloride of chloroalkyl phosphonic acid is easily hydrolyzed by the action of water into the free chloroalkyl phosphonic acid, according to Step (2) above.

Specific aldehydes which are reacted with PCl and hydrolyzed to form chloroalkyl phosphonic acid in accordance with the teachings of the Kabachnik reference and the yields obtained are as follows:

It is apparent that lower aliphatic, aromatic and substituted aromatic aldehydes can be used in the aforedescribed reactions with various degrees of yield.

The selected chloroalkyl phosphonic acid prepared in accordance with the above is reacted with 2-aminoethyl isocyanuric acid to form the isocyanuric acid derivatives of the instant invention according to the general reaction described in Step (3) above which omits showing the intermediate steps of converting the chloroalkylphosphonic acid to the sodium salt, and converting the reaction product to the acid form. The method of this reaction is described in Helv. Chim. Acta. 32, 1175 (1944) in an article by Schwarzenbach et al. The method requires a long reaction time, often several days, relatively high temperatures in the order of 80 C. and relatively high pH of 10-11. Because of hydrolysis of the chlorine-carbon bond in the chloroalkyl phosphonic acid, yields of the desired aminoalkylene phosphonic acid are low and the desired product must be separated from the hydroxy alkyl phosphonic acid secondary reaction product.

A typical reaction wherein chloroalkyl phosphonic acid and 2-aminoethyl isocyanuric acid are reacted to form the isocyanuric acid derivative of the instant invention is as follows:

Two moles of chloroalkyl phosphonic acid and one mole of 2-aminoethyl isocyanuric acid are combined in a concentrated aqueous solution, and sufiicient NaOH is slowly introduced with agitation to achieve and maintain the pH of the reaction mixture at 10-11. Approximately 2.5 to 3 moles of NaOH per mole of chloroalkyl phosphonic acid are generally required in this reaction. The progress of the reaction is monitored by periodic titration of product samples with AgNO to determine ionic chloride. After about 75% of the chloride is reacted, the reaction mixture is neutralized with NaOH and treated with an excess of lead nitrate to form a lead salt precipitate of the phosphonic acid compounds. The precipitate is converted to the free acid by treatment with H 8 and purification of the resulting acid is by conventional recovery and recrystallization techniques.

The acid and salt forms of the isocyanuric acid derivatives falling within Formula I of the present invention have utility in the field of treating water or aqueous systems and function as both a sequestering agent and as a threshold agent. The term threshold as utilized herein refers to the chemical and/ or physical phenomenon that less than stoichiometric quantities of the particular isocyanuric acid derivatives can effectively prevent the precipitation and/or alter the crystal forms of various salts of metallic ions such as calcium, iron, copper and cobalt. In other words, the threshold treatment of water is that technique by means of which less than stoichiometric quantities of the treating agent are added to interfere with the growth of crystal nuclei and thereby prevent the deposition of insoluble deposits. The term is applied, for example, to the treatment of water with polyphosphates and is discussed in references such as US. Pat. No. 2,038,316 and the article by Reitmeier and Buehrer in the Journal of Physical Chemistry, Vol. 44, pages 5 35 to 574 (1939). An additional explanation of the threshold effect will be found in the publications of Hatch and Rice appearing in Industrial Engineering and Chemistry of January 1939, and August 1945.

The acid and ester forms of the isocyanuric acid derivatives falling within Formula I also have utility in the field of flame retardancy for cellulosic materials and specifically function as flame retardants therefor.

In the following examples, all parts are by weight unless otherwise specified.

EXAMPLE I In a 2-liter flask are charged approximately 1480 milli liters of N,N-dimethyl formamide (DMF) and 129 grams of cyanuric acid. While stirring the mixture, a charge of approximately 43 grams of aziridine (ethylene) dissolved in 150 milliliters of DMF is added dropwise over a period of about 45 minutes. The temperature of the reaction mixture rises from about 27 C. to about 29 C. A fine white precipitate is formed during the addition. The overall re action mixture is continuously stirred for a period of 12 hours and then filtered. The resultant wet cake 154 grams) is Washed with absolute ethanol and then dried to obtain 125 grams of product which is characterized as a fine white powder. The yield is approximately 72.7% of theory and the product is analyzed as Z-aminoethyl isocyanuric acid which has the formula:

EXAMPLE II Into a 2-liter flask equipped with a water condenser and dropping funnel are charged approximately 96 grams (0.82 moles) of 70% orthophosphorous acid and 84 grams (0.85 moles) of 37% hydrochloric acid. The resultant mixture in the 2-liter flask is then heated to boiling while adding approximately 28.5 grams (0.17 moles) of the 2-aminoethyl isocyanuric acid prepared as described in Example I above. This Z-aminoethyl isocyanuric acid is added over a period of approximately 30 minutes. Approximately 60 milliliters of water is then charged (after the 30 minute addition period) into said reaction flask in order to obtain a homogeneous, clear solution having a boiling point of approximately 108 C.

The resultant clear solution in the flask is maintained at reflux, and over a period of about 3 hours approximately 27 grams (0.90 moles) of paraformaldehyde is added.

At the end of the addition period, the reaction mixture, which is a clear solution, is cooled to 25 C. An aliquot (50 grams of about 295 grams) of the solution is poured with stirring into milliliters of methanol, and there results a white precipitate. After filtration, the precipitate cake is reslurried in methanol, filtered and washed in the filter with methanol. Upon drying, approximately 2.0 grams of white solids are obtained. Referring to the entire batch, this represents a yield of approximately 11.8 grams of material and 19.3% of theory, based on the 2-aminoethyl isocyanuric acid utilized.

The white solids are analyzed, utilizing the P Nuclear Magnetic Resonance spectra (NMR) (which shows the presence of N-C-P linkage) and elemental analysis. The resultant white solids are found to contain substantially isocyanuryl ethyl imino di(methylenephosphonic acid) having the following structural formula:

The elemental analyses of the white solids obtained is set forth below:

Found, Theory, percent percent 0 24. 67 23. 3 P 14. 3 17. 2 N 14. 1 15. 6 H 5. 1 3. 9

The above analyses show the white solid material to contain some impurities. The reaction product is found to have utility as a sequestration agent as demonstrated in Example IV hereinafter set forth.

EXAMPLE III Into a 2-liter flask equipped with a water condenser and dropping funnel are charged approximately 113 grams (0.82 moles) of diethyl phosphite (C H O) PHO. The phosphite is then heated to about 100 C. while adding approximately 28.5 (0.17 moles) of the 2-aminoethy1 isocyanuric acid prepared as described in Example I above. This 2-aminoethyl isocyanuric acid is added over a period of approximately 10 minutes.

The resultant mixture in the flask is maintained at about l00110" *C., and 27 grams (0.90 moles) of paraformaldehyde is added over a period of about three hours. At the end of the addition period, the reaction mixture is cooled to 25 C. The batch weighs 168 grams and is characterized by being an oily liquid. The oily liquid is analyzed, utilizing the P Nuclear Magnetic Resonance spectra (NMR) and elemental analysis. The resultant material is substantially the ester as shown by the following structural formula:

In order to demonstrate the utility of the isocyanuric acid derivatives falling within Formula I above, the reaction products prepared in Examples II and III are subjected to the sequestration procedure described in the book Coordination Chemistry, Calcium Complexing By Phosphorus Compounds, by C. F. Callis, A. F. Kerst and I. W. Lyons, pages 223-240, Plenum Press, 1969.

Approximately 1 gram of each of the reaction products from Examples 11 and IH is individually and separately mixed with 0.1% by weight sodium oxalate in a 2-liter flask containing 1000 milliliters of water. The pH in each case is adjusted by the addition of sodium hydroxide to a pH 11. Into each solution containing the separate and individual sequestration agents there is titrated a 0.1 molar calcium nitrate solution via the use of a Sargent- Malmstadt automatic titrator, Model SE, and which also measures the turbidity by light transmission. The amount of calcium nitrate solution added to each flask is sufiicient to provide ample data to plot the point of inflection at which the sequestrant-containing solution goes from a relatively clear solution to a turbid one. This inflection point is indicative of the amount of calcium that is sequestered by the particular sequestration agent.

The results of the sequestration test on the reaction products derived from Examples 11 and III show that isocyanuric acid derivatives are good sequestrants for calcium which is one of the major contributors of scale in water used, for example, in cooling towers. Specifically, it is found that the isocyanuric acid derivative prepared in Example II sequesters approximately 6 grams of calcium per 100 grams of said isocyanuric acid derivative.

Thus one application of the isocyanuric acid derivatives falling within Formula I is their use as a sequestration agent in treating aqueous systems containing calcium ions to prevent the formation of calcium salts and scale therein.

EXAMPLEV In order to demonstrate the utility of the esters of the isocyanuric acid derivatives falling within Formula I, approximately 50 grams of the ester prepared in Example -III above are mixed with an inert solvent (carbon tetrachloride) in a 500 milliliter beaker in order to prepare a 10% by weight solution of said ester. After the slurry is prepared, a separate and individual switch of a 3" x 3" undyed cotton cloth is intimately contacted with the slurry by submerging such swatch in the slurry for approximately five minutes. The swatch is withdrawn from the slurry and dried for minutes in an oven which is maintained at a temperature of approximately 80 C. After 15 minutes at 80 C., the temperature is elevated to approximately 150 C. for 10 minutes in order to promote a reaction between the ester and the surface groups on the cotton fibers.

The dried swatch of treated cotton cloth is tested for flame retardancy by positioning the swatch over a Bunsen burner. The flame is adjusted to a point at which the tip of the flame is approximately one inch beneath the treated cotton swatch; an untreated cotton swatch is used as a control for comparative purposes. The flame underneath each of the individual cotton swatches (including the control) is maintained for approximately 35 seconds, and then is removed. Visual observations indicate that while the control sample ignites and burns completely, the treated sample is self-extinguishing and is primarily only charred by this test. Thus, one application of the esters of the isocyanuric acid derivatives falling within Formula I is their use as a fire retardant for cellulose material, such as cotton cloth.

The above examples have been described in the foregoing specification for the purpose of illustration and not limitation. Many variations will naturally suggest themselves to those skilled in the art based on this disclosure, and such variations are also within the scope of this invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An isocyanuric acid derivative having the formula 0 R1 ll dHI 0R OR HN/ NCHzCHN 4 o o o if dn-r -om OH; H

wherein R is hydrogen, phenyl, halo-, nitroor C alkyl-substituted phenyl or C alkyl and R and R are selected from the group consisting of hydrogen, metal ions, ammonium ions, alkyl ammonium ions, C alkyl radicals, C alkenyl radicals, and aryl radicals, said aryl radicals being selected from the group consisting of phenyl, naphthyl, anthryl, and phenanthryl, and C alkyl, hydroxy, haloand amino-substituted derivatives thereof.

2. A compound of Claim 1 wherein R is selected from the group consisting of hydrogen, C alkyl and phenyl.

3. A compound of Claim 1 wherein R and R are each selected from the group consisting of hydrogen, C alkyl and phenyl.

4. A compound of Claim 1 wherein R and R are alkali metal ions selected from the group consisting of sodium, lithium, and potassium.

5. A compound of Claim 1 wherein R and R each comprise one-half of a divalent metal ion selected from the group consisting of calcium, magnesium, zinc, cadmium, iron and copper.

6. A compound of Claim 1 wherein R is H, CH C3H7, C6H5, CH3C6H5, C1C6H5 01' NO2C5H5.

7. A compound of Claim 6 wherein R and R are each selected from the group consisting of hydrogen, C alkyl and phenyl.

8. A compound having the formula 10. A compound which is a metal salt of an acid having the formula References Cited UNITED STATES PATENTS 3,654,169 4/1972 Matzner et a1 260248 JOHN M. FORD, Primary Examiner US. Cl. X.R.

260-502.4 R, 606.5 P, 606.5 F; 2528.l, 8.8; 117136; 252-481 $233? I I STATES rum CERTIFICATE OF CORRECTION ?atent No. 3 ,s3a,124 m September 24, 1974 Inventofla) Edward A. Matzner and Robert s. Mitchell It 1': cu-ufieqzl this error appears in the wow-identified patent and thlt nid'Lattu-l Penn: in hereby corrected as shown below:

Col. 2 line 65 "phosphors" should read phoeph orus Col. 5 line 35 (ethylene) eIiozmld read (ethyleneimine) Col. 7, line 43, switch" should read swatch -v-.

f P Signedahd sealed this 171:1; ay of December 1974.

(SEAL) .Attest HcCOY M. GIBSON JR. Attesting Officer C. MARSHALL DANN 1 Commissioner of. Patents 233? v sums rum omcn I CERTIFICATE OF, CORRECT-ION iatent No. 3 ,838,124 a September 24, 1974 lnvfln fln) Edward A. Matzne r and Robert S. Mitchell It in cnrtifleql that and: appeal in the abafio-id'eatifiid Pltlflt and that uid'tatgnrl Patent in hnuby contend as shown 1:01am:

Col. 2 line 65 "phosphors" should rad phosphorus Col. 5 line 35 (ethylene) shbuld read (ethy'leneimin) Col. 7, line 43, "Switch? should rgad swatch Signed and sealed "this 17m ay of jnec'embr 1974.

(SEAL) Att'est: v

McCOY M. GIBSON JR. I Y c. MARSHALL DANN Attesting Officer Commissioner of Patents 

